Allow overriding max hin ttl.
Patch by Vishy Kasar, reviewed by brandonwilliams for CASSANDRA-5988
Merge branch 'cassandra-1.2' into cassandra-2.0
Allow overriding max hint ttl
Patch by Vishy Kasar and brandonwilliams, reviewed by brandonwilliams
for CASSANDRA-5988
Ninja: use v1 (time) instead of v4 (random) UUID for the batchlog